Process for producing a repair coating on a coated metallic surface

ABSTRACT

A process for producing a repair coating on a metallic surface coated with a corrosion protecting coating A applied with a pretreatment composition, an organic composition or a silicon compound containing composition. Corrosion protecting coating A has been at least partially removed in the area Z, and a thin corrosion protecting coating B containing a silicon compound is applied with a solution or dispersion containing a silane, a silanol, a siloxane, a polysiloxane or a mixture thereof on at least a part of the area Z. A further corrosion protecting coating C which is generated with an organic composition like a primer, a wet-primer, an e-coat, a powder coat, a base-coat or a clear-coat or a composition which is the same or another siloxane composition as for the thin film B may also be applied to coating B.

This application is a continuation application of U.S. Ser. No.12/082,841 filed Apr. 15, 2008, which is a divisional of U.S. patentapplication Ser. No. 10/985,652 filed Nov. 10, 2004, hereby incorporatedby reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to a process for producing a repaircoating on at least one metallic surface that is already coated with atleast one corrosion protecting coating like a primer coating, a paintcoating or a siloxane/polysiloxane rich coating or any combination ofthese coatings. Such repair may be of specific interest in the field ofcar production e.g. after the application of an electrocoat (e-coat), inthe repair of a primed or painted car body or parts of it, in the repairof construction components, in the repair of bodies of aerospace orrailcar bodies and other coated metallic surfaces.

BACKGROUND OF THE INVENTION

During the production of car bodies and other coated metalliccomponents, especially of coated metallic sheets, more preferred forhot, warm or cold formed metallic sheets, there are a lot of points andareas with flaws that may be seen after finishing e.g. the paintingprocess with a multilayer of paints e.g. of a primer coating like anelectrocoated first paint coating, a base-coat and a clear-coat. Theclear-coat may be used on top of the paint system. The flaws may becaused by the presence of particles, fibres, pieces of fluff and othermaterials generating flaws with a diameter or thickness of at least 10μm or seldom of at least 4 μm diameter or thickness or e.g. by theagglomeration of at least predominantly organic material gathering tosmall, but significantly visual elevations in the ground or e.g. by bigpores or craters. Such flaws may occur after every painting stage sothat such areas often are treated by removing at least a part of theclear coating or e-coat or both, perhaps even all the coatings in anarea at and around each flaw so that in the middle of the area typicallythe surface of the blank metallic surface is uncovered and perhaps eventaken away a thin part of the metallic base material. On the other hand,it may be necessary to remove at least one coating in an area that isdamaged or that shows more or less corrosion like any form of rust.Then, e.g. the rust has to be removed. The removal of the coatings insuch areas may occur e.g. by sanding, by sand-blasting, by grinding orby paint stripping the coated metallic components. The paint strippingmay occur with the aid of chemicals. This removal determines the sizeand shape of the removal area Z.

It was one object of the invention to propose a repair coating processwhich may be used in an automated process or may be used in an easier, acheaper or better process than conventional repair processes. It was anobject of the invention to propose a repair process with a less amountof primers or paints to be applied for repair than today typically usedin praxis. It was further on an object of the invention to improve thecorrosion resistance and paint adhesion of such coatings generatedduring a repair process.

SUMMARY OF THE INVENTION

The present invention relates to a process for producing a repaircoating on at least one metallic surface that is coated with at leastone corrosion protecting coating A applied with at least one compositionselected from the group of

A1) pretreatment compositions like activating compositions, passivatingcompositions, phosphating compositions, titanium compound(s) orzirconium compound(s) or both of them containing compositions andafter-rinse-compositions,

A2) organic compositions like primers, wet-primers, welding primers,e-coats, powder coats, base-coats and clear-coats and of

A3) silicon compound(s) containing compositions that are solutions ordispersions containing at least one silicon compound selected fromsilanes, silanols, siloxanes and polysiloxanes and,

whereby the at least one corrosion protecting coating A has been atleast partially removed in the area Z,

whereby a thin corrosion protecting coating B containing at least onesilicon compound is applied with a solution or dispersion containing atleast one silane, at least one silanol, at least one siloxane, at leastone polysiloxane or any mixture of these “siloxane composition”) on atleast a part of the area Z.

Further on, the invention refers to a tool suitable for applying aprocess as indicated before, whereby the tool contains and dispenses acomposition which is a solution or dispersion containing at least onesilicon compound selected from silanes, silanols, siloxanes andpolysiloxanes.

Preferably, the removal area Z is prepared in such way where it isintended to lay open the blank metallic material that only a certainpercentage of this area is laid open, e.g. a surface in the range of 40to 85% of this removal area Z. In such cases, it is easier to coat onthe one-hand-side the blank metallic material completely with a thinfilm B, whereas it is avoided that a thin film B is applied outside theremoval area Z.

After the coating of at least a part of the removal area Z with at leastone thin film of the coating B by applying a siloxane composition, theremay be applied a coating C preferably only within the removal area Z oronly on the removal area Z and in a small rim outside of it. Suchcoating C may preferably be prepared by application of a repair primer,a surface primer, a base-coat, a clear-coat or any combination of these.Alternatively, especially if the coating A that was at least partiallyremoved was a coating A3 originally prepared with the aid of a siloxanecomposition, then it is more preferred to apply a coating C with the aidof a siloxane composition that is applied upon the coating B appliedbefore with the aid of the same or another siloxane composition. In manycases it is preferred that the repair of a area to be repaired does notor nearly not show any difference to the surrounding coated area ifthere is applied at least one further coating C that is applied over thetotal surface.

Additionally, the invention refers to a tool suitable for applying aprocess according to claim 1, whereby the tool is a spray can, a sprayinstrument or a stick having a storage chamber containing a compositionwhich is a solution or dispersion containing at least one siliconcompound selected from silanes, silanols, siloxanes and polysiloxanes.

Additionally, the invention refers to a tool suitable for applying aprocess according to claim 1, whereby the tool contains a paste which isa composition containing at least one silicon compound selected fromsilanes, silanols, siloxanes and polysiloxanes and whereby the tooltransmits or releases a portion of the paste when it is brought intocontact with the surface to be coated.

DETAILED DESCRIPTION OF THE INVENTION

The present invention concerns a repair coating process for the repairof the coatings of coated metallic surfaces to generate coatings beingcorrosion resistant and showing good adhesion for a further on itapplied next coating.

The corrosion protecting coatings A, B, C or any combination, of theseare prepared by applying the respective compositions preferably andtypically in a wet stage as solution or dispersion and by drying.Organic compositions may have optionally been further applied by heatingup to cause a crosslinking. The organic corrosion protecting coatings A2may optionally be coatings of primers or paints or specific organiccompositions like welding primers.

The silanols as well as the siloxanes may be monomers, oligomers,polymers or any mixture of them. Therefore, any of the siloxanecompositions for the coatings A, B, C or any combination of these maycontain any mixture of compounds selected from the group of the monomersof silanes, silanols and siloxanes, of oligomers of silanols andsiloxanes and of polymers of silanols and siloxanes whereby the lastones are polysiloxanes. In the following, the “siloxane composition”means a solution or a dispersion that contains at least one silane, atleast one silanol, at least one siloxane, at least one polysiloxane orany mixture of these.

According to the process of the invention, a thin film B of the siloxanecomposition is applied which is preferably without particles, fibres,pieces of fluff and other materials generating flaws having a diameteror thickness of no more than 10 μm, more preferred of no more than 8 μm,most preferred of no more than 6 μm, especially of no more than 4 μm.

According to the process of the invention, a thin film B of the siloxanecomposition is applied which preferably has a wet film thickness in therange from 0.005 to 40 μm, more preferred in the range from 0.01 to 30μm, most preferred in the range from 0.03 to 15 μm.

The thin film B of the siloxane composition is applied which preferablyhas a dry film thickness in the range from 0.001 to 3 μm, more preferredin the range from 0.005 to 1 μm, most preferred in the range from 0.008to 0.5 μm, often in the range from 0.01 to 0.2 μm. If necessary to reachthe required film thickness, the thin film B may be applied at least twotimes one after the other.

According to the process of the invention, a thin film B of the siloxanecomposition is applied and this thin film is then dried, e.g. at atemperature in the range from 5 to 300° C., more preferred the thin filmB is then dried at a temperature in the range from 10 to 250° C., mostpreferred it is then dried at a temperature in the range from 12 to 150°C., especially it is then dried at a temperature in the range from 14 to125° C.

This thin film B is preferably applied with the siloxane composition anddried by self-drying e.g. at about room temperature or at a temperaturein the range from 8° C. to about 60° C., by heating the coated metallicsubstrate, by heating with hot air, by blowing or heating with a hot gasstream or by any combination of these.

According to the process of the invention, a thin film B of the siloxanecomposition is preferably applied by contacting a tool that contains anddispenses the siloxane composition. In another embodiment, the thin filmB of the siloxane composition is preferably applied by spraying thesiloxane composition e.g. with a spray can like an aerosol can or withan automated spraying instrument like e.g. an airless high pressurespray instrument, especially for a long-term discontinuous spraying ofthe siloxane composition. Especially for a spraying process, it may behelpful to take care for an adequate viscosity of the siloxanecomposition and that no drops will be generated. In a furtherembodiment, the thin film B of the siloxane composition is preferablyapplied by using a tool that has a storage chamber for the siloxanecomposition. Alternatively, the thin film B of the siloxane compositionis preferably applied by using a tool like a brush, like a sponge, likea tampon, like a stick or like a gel-pack. This stick may essentiallyhave the shape of a stick or may essentially have the shape of a box,e.g. a flat box, having essentially the function of a stick like a paintstick. Such stick or box may have a membrane or any similar porousmaterial or alternatively have no membrane and no similar porousmaterial if the solution or dispersion of the siloxane composition hasan adequate consistency e.g. of a paste. Additionally, a thin film B ofthe siloxane composition is preferably applied by using a tool with astorage chamber having a membrane or another porous material with theability to transmit the siloxane composition from the storage chamber tothe working surface of the tool. The materials of the tool that are incontact with the siloxane composition should either not chemically reactwith the siloxane composition or only react in such way and extent thatthe coating and repair process and the properties of the resultingcoatings are not impaired.

According to the process of the invention, the siloxane composition haspreferably a viscosity in the range from 1 to 250 mPa·s measured at 20°C. In some embodiments, the viscosity may show values measured accordingto DIN 53211 4 mm-cup at 20° C. in the range from 5 to 45 s, especiallyin the range from 10 to 40 s. Alternatively, the solution or dispersionof the siloxane composition may have a viscosity in such way that it isa paste.

According to the process of the invention, the siloxane composition isapplied to at least one metallic surface preferably of iron, steel,zinc-coated or zinc-alloy-coated steel, aluminium, aluminium alloy,magnesium alloy, titanium:titanium alloy or to any combination of these.The zinc-containing metallic coatings used may especially be:Electrogalvanised steel, hot-dip-galvanised steel, galvalume®, galfan®and galvannealed®.

Today, many components, car bodies including the bodies e.g. of bussesand lorries or any mounted metallic parts consist of at least twodifferent metallic materials as surface materials which. may be metalliccoatings, metallic sheets, metallic parts or joined metallic elements.Therefore, there may be metallic surfaces one beneath the other, thatbelong to different alloys or even to significantly different metallicmaterials e.g. like steel, zinc-coated steel or aluminium alloys.Processes for coating such “multi-metal” applications must be able tocoat the different metallic materials with an adequate coating quality,especially for corrosion resistance and paint adhesion, which is oftennot self-understanding.

It has been found that many siloxane compositions, especially such withtwo significantly chemically different silicon compounds like mixturescontaining at least one organosiloxane with at least one group e.g.selected from amino groups, epoxy groups, glycidoxy groups, hydroxygroups, isocyanato groups, mercapto groups, (meth)acrylato groups,(poly)sulfur groups, thiol groups, ureido groups, vinyl groups andvinylbenzene groups, and at least one siloxane with multifunctionalgroups showing at least two silyl groups per molecule are especiallysuitable for such multi-metal applications.

According to the process of the invention, the siloxane composition mayeven be successfully applied to at least one surface of at least onepart showing at least two different materials at its surface(s), beingmade of at least one metallic material, of at least one plasticsmaterial like a foil, multilayer, sheet or component of plasticsmaterial, of at least one glass material, of at least one ceramicmaterial, of at least one wooden material or of any mixture of these.

According to the process of the invention, the siloxane composition usedfor the coating. A, B, C or any combination of these may be applied toat least one metallic surface of at least one sheet, to at least onecomplex formed part, to at least one massive part or any mixture ofthese. The siloxane composition may especially be applied to at leastone metallic surface of a coil, of a metallic sheet, of a car bodyincluding bodies e.g. of busses and lorries, of parts of a car, of abody of an aerospace, of a ship, of offshore-equipment, of a railcar orof any parts of them, of parts or composed parts for construction,furniture, devices, equipment or specific elements like lamps—especiallyeither during production or after damage or after long-term use.

Further on, the repair process may not only be applied for the repair offreshly produced components during production, but even for a repaire.g. after any damage or when removing rust during the lifetime of thesecomponents. Therefore, the repair process according to the invention maybe even used e.g. in a workshop for car repair or in the repair ofconstruction elements like bridges or of offshore aggregates afterlong-time use.

According to the process of the invention, the at least one corrosionprotecting coating A has been removed at least partially in the area Ze.g. by grinding, sanding, sandblasting or paint stripping or anycombination of them. The coating(s) A may be removed partially ortotally 1. by only removing a part of the top of the top coating of thecorrosion protecting coating(s) A, 2. by only removing the corrosionprotecting boating A on top of at least two corrosion protectingcoatings A or 3. by removing at least two or even all corrosionprotecting coatings A or 4. by removing all corrosion protectingcoatings and part of the metallic surface, 5. perhaps even by removing afurther intermediate layer of the pretreatment of the metallicsurface(s). Often, there will be any combination of these types ofremovals 1. to 5..Often, there is only the corrosion protecting coatingA on the top of at least two corrosion protecting coatings A removed atthe outer rim of the removal area Z where the removal of the coatings Ais less strong. Often, the only one existing corrosion protectingcoating A respectively all the corrosion protecting coatings A aretotally removed in the middle of the removal area Z. Then there is ofteneven a removal of the surface part of the metallic surface in the middleof the removal area Z. Often, even the very thin zinc-rich metalliccoatings are totally removed in the, middle Of the removal area Z.

According to the process of the invention, at least one corrosionprotecting coating C is applied upon the thin film B whereby the coatingC is generated with an organic composition like a primer, a wet-primer,an e-coat, a powder coat, a base-coat or a clear-coat or with a coatingwith the same or with another siloxane composition as for the thin filmB or with a composition intermediate between the composition of anorganic coating and a siloxane/polysiloxane coating or with a successionof applications of such compositions, whereby at least one coating C mayoptionally be applied on a great portion or on the total surface of thecoated metallic part. In several cases that are to be foreseen, therewill be used at least one composition for the production of at least oneorganic coating C like a primer, perhaps followed by a base-coat andperhaps even then followed by a clear-coat. In other cases, there willbe used at least one composition for the production of at least oneorganic coating C like a base-coat, perhaps followed by a clear-coat. Onthe other hand, in the future perhaps there may repair methods be usedby selecting a composition for a coating C containing at least onesilicon compound selected from silanes, silanols, siloxanes andpolysiloxanes, whereby in many cases the content of the at least onesilicon compound may be at least 30% by weight of the total of solids inthe solution or dispersion of this composition, in some cases at least40% by weight of the total of solids in the solution or dispersion ofthis composition, in several cases at least 50% by weight of the totalof solids in the solution or dispersion of this composition, in severalcases even at least 60% by weight of the total of solids in the solutionor dispersion of this composition, in few cases at least 70% by weightof the total of solids in the solution or dispersion of thiscomposition, in few cases at least 80% by weight of the total of solidsin the solution or dispersion of this composition, in few cases at least90% by weight of the total of solids in the solution or dispersion ofthis composition, in very few cases at least 95% by weight of the totalof solids in the solution or dispersion of this composition, in singularcases even at least 98% by weight of the total of solids in the solutionor dispersion of this composition. In specific embodiments of thisinvention, the coating C may contain constituents as typically containedin organic coatings and at the same time may contain constituents astypically contained in coatings formed from siloxane compositions. Suchcoatings may more or less be intermediate in their compositions and intheir properties between organic coatings and coatings prepared fromsiloxane compositions.

According to the process of the invention, the composition for at leastone coating A containing at least one silicon compound selected fromsilanes, silanols, siloxanes and polysiloxanes may in many cases show acontent of the at least one silicon compound may be at least 30% byweight of the total of solids in the solution or dispersion of thiscomposition, in some cases at least 40% by weight of the total of solidsin the solution or dispersion of this composition, in several cases atleast 50% by weight of the total of solids in the solution or dispersionof this composition, in several cases even at least 60% by weight of thetotal of solids in the solution or dispersion of this composition, infew cases at least 70% by weight of the total of solids in the solutionor dispersion of this composition, in few cases at least 80% by weightof the total of solids in the solution or dispersion of thiscomposition, in few cases at least 90% by weight of the total of solidsin the solution or dispersion of this composition, in very few cases atleast 95% by weight of the total of solids in the solution or dispersionof this composition, in singular cases even at least 98% by weight ofthe total of solids in the solution or dispersion of this composition.

According to the process of the invention, the composition for at leastone coating B containing at least one silicon compound selected fromsilanes, silanols, siloxanes and polysiloxanes may in many cases show acontent of the at least one silicon compound may be at least 30% byweight of the total of solids in the solution or dispersion of thiscomposition, in some cases at least 40% by weight of the total of solidsin the solution or dispersion of this composition, in several cases atleast 50% by weight of the total of solids in the solution or dispersionof this composition, in several cases even at least 60% by weight of thetotal of solids in the solution or dispersion of this composition, infew cases at least 70% by weight of the total of solids in the solutionor dispersion of this composition, in few cases at least 80% by weightof the total of solids in the solution or dispersion of thiscomposition, in few cases at least 90% by weight of the total of solidsin the solution or dispersion of this composition, in very few cases atleast 95% by weight of the total of solids in the solution or dispersionof this composition, in singular cases even at least 98% by weight ofthe total of solids in the solution or dispersion of this composition.

According to the process of the invention, the siloxane composition forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at least.one silicon compound selected from the group of silanes, silanols,siloxanes and polysiloxanes. More preferred, the total content of the atleast one silicon compound is in the range of 0.1 to 250 g/L, morepreferred in the range of 2 to 180 g/L, much more preferred in the rangeof 10 to 120 g/L, e.g. about 0.2, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14,16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50,52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86,88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116 or118 g/L.

Preferably, at least one silane, at least one silanol, at least onesiloxane, at least one polysiloxane or any of these mixtures is chosenwhich is compatible with water, i.e. that the at least one siliconcompound and, Where appropriate, its hydrolysis products, itscondensation products and its reaction products are miscible with thecomponents of the aqueous composition without problems and are stablefor at least several weeks. Preferably, it allows the formation of adefect-free wet film and dry film which, in particular, is essentiallyclosed, essentially uniform and free from craters. In particular, atleast one silane, at least one silanol, at least one siloxane, at leastone polysiloxane, their derivatives, any of their reaction products orany of their mixtures is chosen which renders possible a high corrosionresistance and high adhesion to the coating C. Such chemical reactionmay occur between any constituents present in the solution ordispersion, even with further added or present components like additivesor impurities.

The siloxane composition may More preferred contain predominantly atleast one silane, at least one silanol, at least one siloxane, at leastone polysiloxane, their derivatives, their reaction products or any oftheir mixtures in an aqueous solution or dispersion or in a solution ordispersion containing water and optionally at least one organic solvent.The presence of at least one silane, at least one silanol, at least onesiloxane, at least one polysiloxane, their derivatives, their reactionproducts or any of their mixtures offers the advantage that chemicalbonds like covalent bonds or ionic bonds are formed between thesubstrate and the dried protective film and to primer/paint layers or toother organic or siloxane/polysiloxane coatings possibly subsequently,applied, as a result of which an improved “paint” adhesion is alsoachieved. A further advantage is that suitablesilanes/silanols/siloxanes/polysiloxanes generate crosslinkings likechemical bonds within the dried protective film, which oftenconsiderably improve the strength and the adhesion to the substrate, asa result of which an improved adhesion is achieved in many paintsystems.

Preferably, the siloxane composition suitable for the coating(s) A, B, Cor any combination of these contains at least one acyloxysilane, onealkoxysilane, one silane with at least one amino group such as anaminoalkylsilane, one silane with at least one succinic acid group orsuccinic acid anhydride group, one bis-silyl-silane, one silane with atleast one epoxy group such as a glycidoxysilane, one(meth)acrylato-silane, one multi-silyl-silane, one ureidosilane, onevinylsilane, at least one of its silanols, at least one of itssiloxanes, at least one of its polysiloxanes, at least one of theirderivatives, at least one of their reaction products or any of theirmixtures. The reaction products of the silanes are known in principle insuch systems and are therefore. not mentioned individually. They aretherefore also not referred to further in the following.

The siloxane composition may contain e.g. at least one silane mixed witha content of at least one alcohol, such as ethanol, methanol or propanolor any mixture of them, e.g. of up to 8 wt. %, based on the silanecontent, preferably up to 5 wt. %, particularly preferably up to 1 wt.%, very particularly preferably up to 0.5 wt. %, in particular in amixture a) of at least one aminosilane, such as e.g. bis-amino-silane ormono-amino-silane, with at least one alkoxysilane, such as e.g.trialkoxysilylpropyl-tetrasulfane, or b) one vinylsilane and onebis-silyl-aminosilane or one bis-silyl-polysulfursilane or onebis-silykarninosilane or c) one. aminosilane and onemulti-silyl-functional (=multifunctional) silane like e.g.bis-silyl-alkane or any of its corresponding silanols, siloxanes,polysiloxanes, their derivatives, their reaction products or any oftheir mixtures. In general, thosesilanes/silanols/siloxanes/polysiloxanes which have an alkyl groupespecially with a chain length in the range from 1 to 8 C atoms andwhich contain a functional group which is suitable for reaction with apolymer are preferred in particular.

The siloxane composition preferably contains at least one siliconcompound chosen from the group consisting of:

-   -   3-glycidoxyalkyltrialkoxysilane,    -   3-methacryloxyalkyltrialkoxysilane,    -   3-(trialkoxysilyl)alkyl-succinic acid-silane,    -   aminoalkylaminoalkylalkyldialkoxysilane,    -   beta-(3,4-epoxycycloalkyl)alkyltrialkoxysilane,    -   (3,4-epoxycycloalkyl)alkyltrialkoxysilane,    -   bis(trialkoxysilylalkyl)amine,    -   bis(trialkoxysilypethane,    -   (3,4-epoxyalkyl)trilkoxysilane,    -   gamma-aminoalkyltrialkoxysilane,    -   gamma-methacryloxyalkyltrialkoxysilane,    -   gamma-ureidoalkyltrialkoxysilane,    -   glycidoxyalkyltrialkoxysilane,    -   N-(3-trimalkoxysilyl)alkyl)alkylenediamine,    -   N-beta-(aminoalkyl)-gamma-aminoalkyltrialkoxysilane,    -   N-(gamma-trialkoxysilylalkyl)dialkylenetriamine,    -   polyaminoalkytalkyldialkoxysilane,    -   tris(3-trialkoxysilyl)alkyl)isocyanurate,    -   ueidopropyltrialkoxy)silane,    -   vinyltriacetoxysilane        and any of its corresponding silanots, siloxanes, polysiloxanes,        their derivatives and reaction products.

The siloxane composition preferably contains at least one siliconcompound chosen from the group consisting of:

-   -   3-aminopropyl)silanetriot,    -   3-glycidoxypropyltriethoxysilane,    -   3-glycidoxypropyltrimethoxysilane,    -   3-glycidyloxypropyltrialkoxysilane,    -   3-methacryloxypropyltriethoxysilane,    -   3-methacryloxypropyltrimethoxysilane,    -   3-(triethoxysilyi)propyl-succinic acid-silane,    -   aminoethylaminopropylmethyldiethoxysilane,    -   aminoethylaminopropylmethyldimethoxysilane,    -   aminopropyltrialkoxysilane,    -   beta-(3,4-epoxycyclohexyl)ethyltriethoxysilane,    -   beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,    -   beta-(3,4-epoxycyclohexyl)methyltriethoxysilane,    -   beta-(3,4-epoxycyclohexyl)methyltrimethoxysilane,    -   bis-1,2-(triethoxysilyl)ethane,    -   bis-1,2-(trimethoxysilyl)ethane,    -   (3,4-epoxycyclohexyl)propyltriethoxysilane,    -   (3,4-epoxycyclohexyl)propyltrimethoxysilane,    -   bis(triethoxysilylpropyl)amine,    -   bis(trimethoxysilylpropyl)amine,    -   (3,4-epoxybutyl)triethoxysilane,    -   (3,4-epoxybutyl)trimethoxysilane,    -   gamma-aminopropyltnethoxysilane,    -   gamma-aminopropyltrimethoxysilane,    -   gamma-methacryloxyptopyltriethoxysilane,    -   gamma-methacryloxypropyltrimethoxysilane,    -   gamma-ureidopropyltrialkoxysilane,    -   N-(3-(trimethoxysilyl)propyl)ethylenediamine,    -   N-beta-(aminoethyl)-gamma-aminopropyltriethoxysilane,    -   N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane,    -   N-(gamma-triethoxysilylpropyl)diethylenetriamine,    -   N-(gamma-trimethoxysilylpropyl)diethylenetriamine,    -   N-(gamma-triethoxysilylpropyl)dimethylenetriamine,    -   N-(gamma-trimethoxysilylpropyl)dimethylenetriamine,    -   polyaminoalkylethyldialkoxysilane,    -   polyaminoalkylmethyldialkoxysilane,    -   tris(3-(triethoxysilyl)propyl) isocyanurate,    -   tris(3-(trimethoxysilyl)propyl) isocyanurate,    -   vinyltriacetoxysilane        and any of its corresponding silanols, siloxanes, polysiloxanes,        their derivatives and reaction products.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain a contentof at least one partially hydrolysed silane, of at least one totallyhydrolysed silane, of at least one oligomeric siloxane, of at least onepolymeric siloxane, of at least one polysiloxane or of any mixture ofthese. More preferred, these compositions contain a content of at leastone oligomeric siloxane and of at least one polymeric siloxane. If thereis the need of a higher viscosity, there may be added at least onecompound selected from the group of organic monomers, organic oligomers,organic polymers, at least one thickening agent like a fine-crystallinesilicate like any clay or clay-like material like bentonite, fireclay,kaolinite and zeolithe, any borate, any oxide e.g. like nanocrystallineSiO₂, any organic substance or any mixture containing organic substancee.g. selected from the group of organic materials on the base ofcellulose, (meth)acrylate, (poly)saccharide, starch, and polysiloxane.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain a contentof at least one organosilicon compound having at least one group e.g.selected from amino groups, epoxy groups, glycidoxy groups, hydroxygroups, isocyanato groups, mercapto groups, (meth)acrylato groups,(poly)sulfur groups, thiol groups, ureido groups, vinyl groups andvinylbenzene groups and at least one multifunctional silicon compoundhaving at least two silyl groups per molecule. More preferred, thesecompositions are aqueous solutions or dispersions showing a) a contentof at least one organosilicon compound having at least one group e.g.selected from amino groups, epoxy groups, glycidoxy groups, hydroxygroups, isocyanato groups, mercapto groups, (meth)acrylato groups,(poly)sulfur groups, thiol groups, ureido groups, vinyl groups andvinylbenzene groups in a content in the range of 0.1 to 120 g/L, morepreferred in the range of 0.5 to 80 g/L, much more preferred in therange of 1 to 50 g/L, e.g. about 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 8, 10,12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46,48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82,84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114,116 or 118 g/L, and b) a content of at least one multifunctional siliconcompound having at least two silyl groups in the range of 0:1 to 120g/L, more preferred in the range of 0.5 to 80 g/L, much more preferredin the range of 1 to 50 g/L, e.g. about 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6,8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42,44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78,80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110,112, 114, 116 or 118 g/L.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at leastone silicon compound selected from silanes, silanols, siloxanes andpolysiloxanes as well as a content of at least one organic compound thatis an organic monomer, an organic oligomer, an organic polymer, anorganic copolymer, an organic blockcopolymer or any mixture of these.More preferred, these compositions are aqueous solutions or dispersionsshowing a content of at least one organic material, especially in therange of 0.01 to 180 g/L, more preferred in the range of 0.05 to 30 g/L,e.g. about 0.1, 0.2, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22,24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58,60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94,96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 120, 124, 128, 132,136, 140, 144, 148, 152, 156, 160, 164, 168, 172 or 176 g/L. The weightratio of the at least one organic compound to the at least onesilane/silanol/siloxane/polysiloxane may be in the range from 0.001:1 to4:1. preferably in the range from 0.05:1 to 2.5:1. more preferred in therange from 0.1:1 to 1.8:1. most preferred in the range from 0.2:1 to1.5:1. especially in the range of about 0.3:1. about 0.4:1. about 0.5:1.about 0.6:1. about 0.7:1; about 0.8:1, about 0.9:1. about 1:1. about1.1:1. about 1.2:1. about 1.3:1 or about 1.4:1. In some embodiments,there may be at least one fluoride, at least one complex fluoride orboth be added to such mixtures. Further on, the organic film-formingagent to be used for the organic coating or the organic coating may insome cases preferably contain at least one component based on:

-   a) monomers, oligomers, polymers, copolymers, blockcopolymers or any    of their mixtures, each being preferably based on:    -   acryl, butadiene, epoxy, ethylene, melamine, methacryl,        polycarbonate, polyester, polyether, polyurethane, styrene,        vinyl or any mixture of these,-   b) or based on copolymers, preferably of:    -   acrylic-polyester-polyurethane copolymer,    -   acrylic-polyester-polyurethane-styrene copolymer,    -   acrylic acid ester,    -   acrylic acid ester-methacrylic acid ester, optionally with free        acids or acrylonitrile,    -   ethylene-acrylic mixture,    -   ethylene-acrylic copolymer,    -   ethylene-acrylic-polyester copolymer,    -   ethylene-acrylic-polyurethane copolymer,    -   ethylene-acrylic-polyester-polyurethane copolymer,    -   ethylene-acrylic-polyester-polyurethane-styrene copolymer,    -   ethylene-acrylic-styrene copolymer,    -   polyester resins with free carboxyl groups combined with        melamine-formaldehyde resins,    -   a synthetic resin mixture or/and copolymer based on acrylate and        styrene,    -   a synthetic resin mixture or/and copolymer based on        styrene-butadiene,    -   a synthetic resin mixture or/and copolymer of acrylate and        epoxide,    -   based on an acrylic-modified polyester containing carboxyl        groups together with melamine-formaldehyde and ethylene-acrylic        copolymer;    -   polycarbonate-polyurethane,    -   polyester-polyurethane,    -   styrene,    -   styrene-vinyl acetate,    -   vinyl acetate,    -   vinyl ester,    -   vinyl ether        or any mixture of these or on any mixture of a) and b).

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at leastone silicon compound selected from silanes, siloxanes and polysiloxanesas well as a content of at least one acid like acetic acid, glacialacetic acid, another carbonic acid, sulphuric acid, hydrochloric acid,nitric acid, fluoric acid, any phosphorus containing acid or any mixtureof these. More preferred, these compositions are aqueous solutions ordispersions showing only a small content of at least one acid, mostpreferred in the range of 0.1 to 50 g/L, especially in the range of 0.15to 30 g/L , e.g. about 0.5, 1, 2, 4, 8, 12, 16, 20, 24, 26, 28, 30, 32,34, 36, 38, 40, 42, 44, 46 or 48 g/L or even no content of any acid. Thecontent of acids may be added to the composition or may be produced bychemical reactions in the composition e.g. by the reaction of at leastone silicon compound with water during hydrolysis.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at leastone silicon compound selected from silanes, siloxanes and polysiloxanesas well as a content of at least one organic solvent like an alcohollike methanol, ethanol, propanol or any mixture of these. Morepreferred, these compositions are aqueous solutions or dispersionsshowing only a small content of at least one organic solvent, mostpreferred in the range of 0.1 to 200 g/L, especially in the range of 1to 150 g/L, e.g. about 0.5, 1, 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40,44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 64, 88, 92, 96, 100, 104, 108,112, 116, 120, 124, 128, 132, 136, 140, 144 or 148 g/L or even nocontent of organic solvent.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at leastone silicon compound selected from silanes, silanols, siloxanes andpolysiloxanes as well as a content of at least one compound containingtitanium, hafnium, zirconium, aluminium or boron or even any mixture ofthese. More preferred, there is an addition of at least one compoundselected from compounds of complex fluorides or carbonates or nitratesor organic compounds of titanium, hafnium, zirconium, aluminium andboron or any mixture of these. Preferably, these compositions areaqueous solutions or dispersions showing a content of at least onecompound containing titanium, hafnium, zirconium, aluminium or boron oreven any mixture of these in the range of 0.01 to 100 g/L, morepreferred in the range of 0.05 to 50 g/L, e.g. about 0.1, 0.2, 0.5, 1,2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36,38, 40, 42, 44, 46 or 48 g/L. The weight ratio of thesilanes/silanols/siloxanes/polysiloxanes to the sum of compoundscontaining titanium, hafnium, zirconium, aluminium and boron maypreferably be in the range from 0.01:1 to 6:1. preferably in the rangefrom 0.05:1 to 4.5:1. more preferred in the range from 0.1:1 to 2.8:1.most preferred in the range from 0.2:1 to 2.5:1. especially in the rangeof about 0.3:1. about 0.4:1. about 0.5:1. about 0.6:1. about 0.7:1.about 0.8:1, about 0.9:1. about 1:1. about 1.1:1. about 1.2:1. about1.3:1. about 1.4:1, about 1.5:1. about 1.6:1. about 1.7:1. about 1.8:1.about 1.9:1. about 2.0:1, about 2.1:1. about 2.2 1. about 2.3:1 or about2.4:1. In some embodiments, there maybe at least one fluoride, at leastone complex fluoride or both be added to such mixtures.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at leastone silicon compound selected from silanes, silanols, siloxanes andpolysiloxanes as well as a content of at least one additive selectedfrom the group of particles with a grain size below one micron of all orof nearly all particles, surfactants like at least one nonionicsurfactant, dyes, fluorescing agents, biocides, pH adjusting agents,chelates, crosslinkers suitable for chemical crosslinking upon thermalinfluence, photoinitiators and substances for the generation of a gel.The particles may be inorganic particles or organic particles or both.These particles may be corrosion protection agents, electricallyconductive, coloured or colour-free. The surfactants may aid in theimprovement of the wettability and in the homogeneity of the generatedthin film. The coloured particles, the dyes, the fluorescing agents orany mixture of these may help to increase the visibility of thegenerated thin film, which is typically not to be seen or is only beseen as a milky film or a film with a different glance or without anycolouring with the naked eye or without any optical aids like UV light.The pH adjusting agents like any acid(s) or any basic substance like NH₃solution may aid to lower or increase the pH. The biocides may help tosuppress biological activity and further chemical variation which maynegatively influence the performance of the compositions. The chelatingagents may serve in particular to stabilize metallic compounds presentin water. They are particularly suitable if they have only a lowreactivity in the aqueous composition and if they are at least partlydecomposed within the process conditions used and the metal ions for thebonding or chemical reaction are liberated. If they are too reactive,the organometallic compounds may react prematurely with other chemicalcompounds, such as silanes. Preferably, the chelates are hydrophilic,stable to hydrolysis, stable to water, form stable hydrolysates or showany mixture of these properties. Preferably, a silane or a chelate orboth is/are chosen which is/are compatible with water and moreover insuch cases together with an organic film-forming agent is chosen andwhich has the same properties as mentioned before for the silane or forthe chelate. The crosslinkers for chemical networking by application ofa higher temperature, often in the range from 80 to 300° C., likecompounds on the base of isocyanate, isocyanurate, melamine or anymixture of them, help to generate a denser network by chemical reactionat higher temperature. The photoinitiators may help to generate denser,networks with the aid of radical polymerisation if there are adequatemonomers, oligomers, polymers, copolymers, blockcopolymers or any oftheir mixtures present. More preferred, these compositions are aqueoussolutions or dispersions showing a content of at least one type ofadditive of the group mentioned above in the range of 0.01 to 150 g/Lfor each additive type as mentioned in the group above, more preferredin the range of 0.5 to 120 g/L. each, e.g. about 1, 2, 3, 4, 6, 8, 10,12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46,48:50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82,84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114,116 or 118 g/L each.

The at least one metal chelate is preferably chosen from chelatecomplexes based on acetylacetonates, acetoacetates, acetonates,alkylenediamines, amines, lactates, mono-carboxylic acids,bis-carboxylic acids, citrates, glycols or any of their mixtures. The atleast one metal chelate is preferably based on:

-   -   acetylacetonate,    -   acetoacetate,    -   di-n-alkoxy-bisalkyl acetoacetate,    -   hydroxyalkylenediamine triacetate,    -   trialkanolamine,    -   trialkylenetetramine alkali metal lactate,    -   alkanolamine,    -   alkyl acetatoacetate,    -   alkylenediamine tetraacetate,    -   ammonium lactate,    -   citrate,    -   dialkyl citrate,    -   dialkyl ester-citrate,    -   dialkylenetriamine,    -   diisoalkoxybisalkyl acetoacetate,    -   diisopropoxybisalkyl        or any mixture of these.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of these are solutions or dispersions that contain at leastone silicon compound selected from silanes, silanols, siloxanes andpolysiloxanes as well as. a content of at least one nitrogen containingagent like nitrate, nitrite or a guanidine compound like nitroguanidine.Such nitrogen containing agent may contain at least one nitrogencontaining group or may release such groups. More preferred, thesecompositions are aqueous solutions or dispersions showing a content ofat least one agent in the range of 0.01 to 60 g/L, more preferred in therange of 0.05 to 40 g/L, e.g. about 0.1, 0.2, 0.5, 1, 2, 3, 4, 6, 8, 10,12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36 or 38 g/L.

According to the process of the invention, the siloxane compositions forthe generation of the corrosion protecting coating(s) A, B, C or anycombination of them are solutions or dispersions that contain at leastone silicon compound selected from silanes, silanols, siloxanes andpolysiloxanes that has at least one functional group selected from thegroup consisting of amino, epoxy, glycidoxy, isocyanato, mercapto,(meth)acrylato, (poly)sulfur, ureido, vinyl and vinylbenzene.

According to another aspect of the invention, a tool suitable forapplying a process according to the invention contains and dispenses acomposition which is a solution or dispersion containing at least onesilicon compound selected from silanes, silanols, siloxanes andpolysiloxanes. More preferred, the tool contains a composition whichcontains predominantly at least one silicon compound.

According to a further aspect of the invention, a tool suitable forapplying a process according to claim 1 is a spray can, a sprayinstrument or a stick having a storage chamber containing a compositionwhich is a solution or dispersion containing at least one siliconcompound selected from silanes, silanols, siloxanes and polysiloxanes.More preferred, the tool contains a composition which containspredominantly at least one silicon compound.

According to a further aspect of the invention, a tool suitable forapplying a process according to claim 1 contains a paste which is acomposition containing at least one silicon compound selected fromsilanes, silanols, siloxanes and polysiloxanes and whereby the tooltransmits or releases a portion of the paste when it is brought intocontact with the surface to be coated. More preferred, the tool containsa composition which contains predominantly at least one siliconcompound.

Such tools may contain the siloxane composition in a concentrationadequate for the coating of the removal area Z. Preferably, thisconcentration is adequate to generate a wet film and dry film ofadequate wet film thickness and of adequate dry film thickness. Therequired corrosion protection and adhesion may be gained during dryingor during drying and crosslinking or during drying and chemicalreacting.

With the process of the invention, it is possible to use the followingrepair process successions:

A) First, the siloxane composition .may be applied onto the removal areaZ at least partially. Then, a coating C may be applied more or less inthe region of the removal area Z with a composition like a repair primeror a surface primer or a further siloxane composition or any mixturebetween an organic and a siloxane composition. It may be sometimesnecessary to level this area coated with the coating C e.g. by grindingor lapping, especially so that there are no edges to be seen at theboarder of these coatings, even perhaps under a further paint coating.It was found that such a system with a primer as coating C shows anastonishingly high corrosion resistance and a better paint adhesion thanthe system as typically used without any siloxane composition.

B) Alternatively, first, the siloxane composition was applied onto theremoval area Z at least partially. Then, no coating C like a repairprimer or a surface primer was used in the region of the removal area Z.Instead of this, a further coating was applied all over the metallicsheet resp. part, covering in the repair zone even the coating Bprepared with the siloxane composition. Then, there is the possibility,but no necessity, to equalize the depth generated in the removal area Ze.g. by applying a greater coating thickness of this coating which maybe applied e.g. by a base-coat or a clear-coat or a combination ofthese. This has the advantage, to save the process step of applying therepair primer resp. surface primer and even to level this area e.g. bygrinding or lapping. Nevertheless, the corrosion resistance of thismultilayer system seems to be a bit better than the normal unrepairedpaint system just beneath. For the repair of coated metallic materiale.g. of constructions like bridges, furniture, devices and equipment, inthe repaired areas the primer coatings C and perhaps even a next primercoating may be thinner than normal so that costs could be furtherreduced.

It was surprising that it was possible—e.g. only by spraying or with aneasy tool like a sponge—to apply a siloxane composition to generate athin film B without any practical problems and without any loss ofcoating quality although there was a manual application which handlingwas only partially controlled. Even for an application of an aqueoussiloxane containing solution by manual handling, where an inhomogeneousor partially insufficient thick coating may perhaps occur, no problemoccurred showing indications for a non-coated and therefore notcorrosion-protected area or for too thin or too thick coated areas.Therefore, it looks like that even for the manual handling of a tool nosituation does occur easily where there remain insufficiently protectedareas of the coating B. This means that the manual application processseems to be a robust process.

It was further surprising that a process may be developed which maybe—especially during car body preparation in car production—appliedin-line. Up to now, a repair of painted car bodies with at least onerepair area per car body, which is necessary for a certain, sometimeseven very high percentage of car bodies, is typically carried out byseparating such car bodies and repair them in separate areas. Due to thepossibility of an easier and quicker application of the siloxanecomposition than of the actually used coatings, the repair process mayproceed immediately and in-line.

Additionally, it was surprising that a siloxane composition according tothe invention shows a good corrosion resistance and paint adhesion whenthis composition is applied without a prior cleaning step and withoutapplying as a further coating an e-coat, a repair primer, another typeof primer or paint or any combination of these, for example in at leasttwo coatings. This result was as outstanding, as at least one coating Bwas applied with the aid of a siloxane composition that typically allowsthe generation of a dry film thickness in the range from 0.01 to 0.1 μmof the coating B and as e.g. the corrosion resistance is strongly afunction of the coating thickness. Typically, a single primer or paintcoating shows a dry film thickness in the range from 10 to 50 μm:

Typically, the paint system as multiplayer of mostly at least threecoatings one above the other of at least one primer or e-coat and of atleast one paint has a thickness in the dry state in the range from 30 to150 μm. For such dry film thicknesses, it is no problem to generate agood corrosion resistance.

SPECIFIC EXAMPLES AND COMPARISON EXAMPLES

The following sections describe specific examples and comparisonexamples with the target to show some of the possible process varieties,composition varieties and the effects related thereto more in detail andnot to limit the invention.

Section 1: Preparation of the coated metal sheets and application of therepair coating B

For each test, fifteen metal sheets from hot-dip-galvanised steel weretaken having a zinc phosphate coating and an e-coat electrocoated on thezinc phosphate coating. The thickness of the zinc phosphate coating wasabout 6 μm, the thickness of the e-coat was about 20 μm. In the middleof each such coated metal sheet, these coatings were sanded so thatthere the blank metal sheet was to be seen in the middle of the sheet,of which a thin metal surface has been removed by sanding, too. Then,immediately after sanding, a clean wipe releasing no fibers and nopieces of fluff was impregnated with pure water so that is was wet. Thiswet clean wipe was used to wipe along the whole removal areas Z to cleanthem thoroughly from dust and from further fine parts that remained fromthe sanding. Then these areas were dried with a further clean wipe sothat there was no or only a very thin water film remaining. Then,immediately after cleaning, the siloxane composition was applied to theremoval areas Z to generate a coating B on the freshly prepared andclean removal areas.

Then in Test 1. this metallic surface as well as small rims of it werecoated with an aqueous siloxane composition of a mixture ofsilanes/silanols/siloxanes with a high content of amino groups and oftitanium hexafluoride in a weight ratio of 1:3. This siloxanecomposition was sprayed on to the center of the removal area Z in suchway that there was generated a dry film on the whole blank metallicsurface as well as on a small neighbouring rim of the coated area wherethe coating B was reduced in thickness by sanding. These parts of theremoval area Z, but not all of the sanded parts of the removal area Z,were coated with this coating B. There was no thin film B sprayed on tonon-sanded parts outside the removal area Z. The generated coatings Bwere totally 10. and obviously homogeneously coated with a dry filmthickness of about 25 to about 80 μm thickness depending on andproportional to the concentration of all these additions together inwater of 5, 10 resp. 15% by weight. it was further taken care that theredid not occur any drops of the silane/silanol/siloxane containingaqueous solution and that the wet film of the siloxane composition wasin about homogeneously and of in about equal thickness. This wet thinfilm B was dried by hot air at 80° C. for 5 minutes to generate acoating B. Then the corrosion resistance as well as the paint adhesionwas tested.

In Test 2. the same procedure was undertaken, but additionally, in thesiloxane coated removal area Z a repair primer with a thickness of about20 μm was applied, dried and heated to the temperature of crosslinking.Then, the area of the repair primer was finely grinded to removethickness differences at its rims. Finally a clear-coat was applied andthermally crosslinked. Then the corrosion resistance as well as thepaint adhesion was tested.

In the Tests 3 and 4. the same procedures as in the Tests 1 and 2 wereused, but with the difference, that as aqueous siloxane composition anaqueous silane/silanol/siloxane composition was applied containing amixture of alkoxysilanes/alkoxysilanols/alkoxysiloxanes having aminogroups and a mixture of silanes/silanols/siloxanes having predominantlytwo silyl groups in a weight ratio of 1:1.

What is claimed is:
 1. A process comprising: applying a corrosionprotection coating to a metallic surface; removing the corrosionprotection coating from the metallic surface in at least and area Z ofthe metallic surface; forming a repair coating on at least a part of thearea Z by applying a solution or dispersion consisting of at least onesilicon compound selected from the group consisting of a silane, asilanol, a siloxane, and a polysiloxane, on at least a part of the areaZ.
 2. The process of claim 1 wherein the solution or dispersioncomprises Ti or Zr.
 3. The process of claim 1, wherein the solution ordispersion coating comprises a complex fluoride of Ti or Zr.
 4. Theprocess of claim 1, wherein the solution or dispersion comprises atleast one of a nitrate, a nitrite, a surfactant, an acid or a base. 5.The process of claim 1, wherein the solution or dispersion comprises anion selected from the group consisting of Al, Co, Fe, Mg, Mn, Su or Zn.6. The process of claim 1, wherein the solution or dispersion containsfree fluoride.
 7. The process of claim 1, wherein the solution ordispersion further comprises a fluoride, a complex fluoride, or nitrateof titanium, hafnium, zirconium or aluminum.
 8. A process comprising:applying a corrosion protection coating to a metallic surface, removingthe corrosion protection coating from the metallic surface in at leastan area Z of the metallic surface; and forming a repair coating on atleast a part of the area Z by applying a solution or dispersioncomprising an acyloxysilane, one alkoxysilane, one silane with at leastone amino group, a silane with at least one succinic acid group orsuccinic acid anhydride group, a bis-silyl silane, a silane with atleast one epoxy group, a (meth)acrylato-sihine, a multi-silyl-silane, aureidosilane, a vinylsilane, a silariol a siloxane.
 9. The process ofclaim 8, wherein the solution or dispersion comprises Ti or Zr.
 10. Theprocess of claim 8, wherein the solution or dispersion comprises acomplex fluoride of Ti or Zr.
 11. The process of claim 8, wherein thesolition or dispersion comprises at least one of a nitrate, a nitrite, asurfactant, an acid or a base.
 12. The process of claim 8, wherein thesolution or dispersion comprises an ion selected from the groupconsisting of Al, Co, Fe, Mg, Mn, Su or Zn.